Aluminum Release from Solid‐Phase Components of Forest Soil Leached with Citric Acid

Abstract

Abstract The solubility of solid‐phase Al pools within size fractions of a forest soil A horizon was evaluated using aqueous citric acid to determine the rates and cumulative amounts of Al released over time. Particle‐size fractions were also characterized by the nature and sizes of various solid‐phase Al pools present. The magnitude of particular Al pools explained the rate of Al release over time. Sizes of organically bound Al pools (quantified by Na pyrophosphate extraction) were similar to those amounts of Al rapidly released in the early stages of citric acid leaching, indicating that organically bound Al was the most soluble of the solid‐phase Al pools. The steady, but slower, subsequent release of soil Al is attributed to solubilization from primary and secondary crystalline lattice minerals. Results reaffirm the use of Na pyrophosphate extraction as a method for quantifying reactive solid‐phase soil Al pools because of its ability to extract a unique and reactive Al pool from a range of soil particle sizes.